Improvement in cut-off valves xfor  steam-engines



R. SANDE'RSON. Gutj-offVa1ve for Steam-Engines. No. 206,975. PatentedAug. 13.1878.

UNITTEDSTATES PATENT OFFICE.

ROBERT SANDERSON, OF CLEVELAND, OHIO.

iMPROVElVIENT IN CUT-OFF VALVES ,FOR STEAM-ENGINES.

Specification `forming part of Letters Patent No. 206,975, dated August13, 1878; application filed July 17, 1876.

To all whom it may concern:

Be it known that I, ROBERT SANDERsoN,

of Cleveland, in the county of Cuyahoga and State of Ohio, have inventeda new and useful Improvement in Out-Oif Valves for Steam- Engines, whichimprovement is fully set forth in the following specification,'referencebeing had to the accompanying drawings.

The object ot' my invention is to secure a higher lift and alonger-continued opening of thc cut-off valve when the speed of theengine is decreased, either by increased work or diminished pressure ofsteam, and less lift and shorter cut-oft' when by any means the speed isincreased beyond the desired rate; also, to provide against damageresulting from any accident by which the governor would be stopped orthe engine suddenly released from its work, by thecombination of thetapering spiral-shaped cam shown in Figures l and 2 with the governor,which it is not deemed necessary to show, and any suitable gearing tothe engine-shaft, giving the cam a rotary and longitudinal mot-ion onthe shaft J, Fig. 5, operating the cut-off valve by means of the rolleror toe F, Fip. 4, ou the valve-stem K, as hereinafter described; and twoof such movements, as is represented by one drawing, may be used whenthe engine has ports at each end, and by this means take oft' nearly"all the steam-pressure from the main valve, and in'a great measure savethe friction arising from such pressure when ports are openedalternately.

In the accompanying drawings, Fig. l represents an end view of the cam.Commencing at the point a in Figs. 2 and 3, the unshaded portion in Fig.l shows the increase ot' the lift of the cam, also seen at b and c inFig. 2, from a slight movement from b to a full movement at c, and aninstantaneous cut-off at b to a, full-stroke cut-'offat c, and anydesired cut-v olii1 between the points b and c, as will be readily seenby following the dott-ed line and full line at E, Fio. 2.

H represents a fork turning inthe groove G in Fi 0. 3, by means ot'which, in connection with the rod I, which connects it with thegovernor, the cam is moved backward and forward on the shaft J, andunder the roller or toe F, to accomplish the object already set forth. dis an adjustable screw for graduating the spring l on the valve-stem.IC.

The operation is as follows: When the engine is running too slow thedropping of the governor-balls moves the cam in the direction of C, anda higher and longer-continued lift given to the valve, and the reversewhen the engine runs too fast.

To secure safety the cam is turned down at O and 1),-so that no liftwill be given to the valve when either ot' these points is under the.roller or toe F. Thus, by properly adjusting the connections, thestopping of the governor by any accident moves the cam so the point Dwill be under the roller vor toe F and the engine stopped, and anyunusual speed moves the cam so that the point() will be under the rolleror toe, and the engine checked until it would again commence using steamat the point I1".-

I am aware that spiral-shaped and tapering 1 cams have been used forvalve-gear, iu some ot which a narrow space has been left ot' acylindrical form 5 but I do not know that any such spaces have been usedfor the purpose oi' allowing the toe of the valve to drop down and checkthe engine thereby, as previously described herein; and I also disclaimthe device shown in the patent of YV. Wright, of

`october 1o, 1871, No. 119,908.

I claim- In a cut-off valve, the spiral-shaped and tapering elongatedcam E, having at the ends the safety-cylinders C and D, formed above thesurface of the shaft, constructed and arranged substantially as andforthe purpose described.

ROBERT SANDERSON.

Witnesses:

THOMAS M. HIGHT, JOHN PoLLocK.

